Clearing the Haze Around 'Constructive Trust' in Family Law

Hey CLATers, I've been stuck with the concept of 'constructive trust' in Family Law. Our textbooks explain it in circles, but I'm yet to grasp the nitty-gritty. Can someone from the community share a real-life example or definition that's simple and clear? For instance, in the context of the 2015 SC judgment in Parag Parag v. Parag Parag, what exactly is a constructive trust in cases of undue influence or secret trust? A concrete example from Indian law would be much appreciated.